bridge: add support for user mode STP

This patchset based on work by Aji_Srinivas@emc.com provides allows
spanning tree to be controled from userspace.  Like hotplug, it
uses call_usermodehelper when spanning tree is enabled so there
is no visible API change. If call to start usermode STP fails
it falls back to existing kernel STP.

Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>

8 files changed, 96 insertions, 17 deletions

diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
index f3a2e29be40c..cf10b8f2a1c7 100644
--- a/net/bridge/br_if.c
+++ b/net/bridge/br_if.c
@@ -203,7 +203,7 @@ static struct net_device *new_bridge_dev(const char *name)
         memcpy(br->group_addr, br_group_address, ETH_ALEN);
 
         br->feature_mask = dev->features;
-        br->stp_enabled = 0;
+        br->stp_enabled = BR_NO_STP;
         br->designated_root = br->bridge_id;
         br->root_path_cost = 0;
         br->root_port = 0;
diff --git a/net/bridge/br_ioctl.c b/net/bridge/br_ioctl.c
index 147015fe5c75..eda0fbfc923a 100644
--- a/net/bridge/br_ioctl.c
+++ b/net/bridge/br_ioctl.c
@@ -137,7 +137,8 @@ static int old_dev_ioctl(struct net_device *dev, struct ifreq *rq, int cmd)
                 b.topology_change = br->topology_change;
                 b.topology_change_detected = br->topology_change_detected;
                 b.root_port = br->root_port;
-                b.stp_enabled = br->stp_enabled;
+
+                b.stp_enabled = (br->stp_enabled != BR_NO_STP);
                 b.ageing_time = jiffies_to_clock_t(br->ageing_time);
                 b.hello_timer_value = br_timer_value(&br->hello_timer);
                 b.tcn_timer_value = br_timer_value(&br->tcn_timer);
@@ -251,7 +252,7 @@ static int old_dev_ioctl(struct net_device *dev, struct ifreq *rq, int cmd)
                 if (!capable(CAP_NET_ADMIN))
                         return -EPERM;
 
-                br->stp_enabled = args[1]?1:0;
+                br_stp_set_enabled(br, args[1]);
                 return 0;
 
         case BRCTL_SET_BRIDGE_PRIORITY:
diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
index a14ac51753e6..5e84ade129ca 100644
--- a/net/bridge/br_netlink.c
+++ b/net/bridge/br_netlink.c
@@ -165,7 +165,7 @@ static int br_rtm_setlink(struct sk_buff *skb,  struct nlmsghdr *nlh, void *arg)
                 return -EINVAL;
 
         /* if kernel STP is running, don't allow changes */
-        if (p->br->stp_enabled)
+        if (p->br->stp_enabled == BR_KERNEL_STP)
                 return -EBUSY;
 
         if (!netif_running(dev) ||
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index 3adacdf3406f..974feccd28b1 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -26,7 +26,10 @@
 #define BR_PORT_BITS    10
 #define BR_MAX_PORTS    (1<<BR_PORT_BITS)
 
-#define BR_VERSION      "2.2"
+#define BR_VERSION      "2.3"
+
+/* Path to usermode spanning tree program */
+#define BR_STP_PROG     "/sbin/bridge-stp"
 
 typedef struct bridge_id bridge_id;
 typedef struct mac_addr mac_addr;
@@ -107,7 +110,13 @@ struct net_bridge
 
         u8                              group_addr[ETH_ALEN];
         u16                             root_port;
-        unsigned char                   stp_enabled;
+
+        enum {
+                BR_NO_STP,              /* no spanning tree */
+                BR_KERNEL_STP,          /* old STP in kernel */
+                BR_USER_STP,            /* new RSTP in userspace */
+        } stp_enabled;
+
         unsigned char                   topology_change;
         unsigned char                   topology_change_detected;
 
@@ -127,7 +136,6 @@ static inline int br_is_root_bridge(const struct net_bridge *br)
         return !memcmp(&br->bridge_id, &br->designated_root, 8);
 }
 
-
 /* br_device.c */
 extern void br_dev_setup(struct net_device *dev);
 extern int br_dev_xmit(struct sk_buff *skb, struct net_device *dev);
@@ -209,6 +217,7 @@ extern void br_become_designated_port(struct net_bridge_port *p);
 /* br_stp_if.c */
 extern void br_stp_enable_bridge(struct net_bridge *br);
 extern void br_stp_disable_bridge(struct net_bridge *br);
+extern void br_stp_set_enabled(struct net_bridge *br, unsigned long val);
 extern void br_stp_enable_port(struct net_bridge_port *p);
 extern void br_stp_disable_port(struct net_bridge_port *p);
 extern void br_stp_recalculate_bridge_id(struct net_bridge *br);
diff --git a/net/bridge/br_stp.c b/net/bridge/br_stp.c
index f9ff4d57b0d7..ebb0861e9bd5 100644
--- a/net/bridge/br_stp.c
+++ b/net/bridge/br_stp.c
@@ -370,11 +370,11 @@ static void br_make_blocking(struct net_bridge_port *p)
 static void br_make_forwarding(struct net_bridge_port *p)
 {
         if (p->state == BR_STATE_BLOCKING) {
-                if (p->br->stp_enabled) {
+                if (p->br->stp_enabled == BR_KERNEL_STP)
                         p->state = BR_STATE_LISTENING;
-                } else {
+                else
                         p->state = BR_STATE_LEARNING;
-                }
+
                 br_log_state(p);
                 mod_timer(&p->forward_delay_timer, jiffies + p->br->forward_delay);     }
 }
@@ -384,6 +384,10 @@ void br_port_state_selection(struct net_bridge *br)
 {
         struct net_bridge_port *p;
 
+        /* Don't change port states if userspace is handling STP */
+        if (br->stp_enabled == BR_USER_STP)
+                return;
+
         list_for_each_entry(p, &br->port_list, list) {
                 if (p->state != BR_STATE_DISABLED) {
                         if (p->port_no == br->root_port) {
diff --git a/net/bridge/br_stp_bpdu.c b/net/bridge/br_stp_bpdu.c
index b9fb0dc4ab12..60112bce6698 100644
--- a/net/bridge/br_stp_bpdu.c
+++ b/net/bridge/br_stp_bpdu.c
@@ -33,9 +33,6 @@ static void br_send_bpdu(struct net_bridge_port *p,
 {
         struct sk_buff *skb;
 
-        if (!p->br->stp_enabled)
-                return;
-
         skb = dev_alloc_skb(length+LLC_RESERVE);
         if (!skb)
                 return;
@@ -75,6 +72,9 @@ void br_send_config_bpdu(struct net_bridge_port *p, struct br_config_bpdu *bpdu)
 {
         unsigned char buf[35];
 
+        if (p->br->stp_enabled != BR_KERNEL_STP)
+                return;
+
         buf[0] = 0;
         buf[1] = 0;
         buf[2] = 0;
@@ -117,6 +117,9 @@ void br_send_tcn_bpdu(struct net_bridge_port *p)
 {
         unsigned char buf[4];
 
+        if (p->br->stp_enabled != BR_KERNEL_STP)
+                return;
+
         buf[0] = 0;
         buf[1] = 0;
         buf[2] = 0;
@@ -157,9 +160,13 @@ int br_stp_rcv(struct sk_buff *skb, struct net_device *dev,
         br = p->br;
         spin_lock(&br->lock);
 
-        if (p->state == BR_STATE_DISABLED
-            || !br->stp_enabled
-            || !(br->dev->flags & IFF_UP))
+        if (br->stp_enabled != BR_KERNEL_STP)
+                goto out;
+
+        if (!(br->dev->flags & IFF_UP))
+                goto out;
+
+        if (p->state == BR_STATE_DISABLED)
                 goto out;
 
         if (compare_ether_addr(dest, br->group_addr) != 0)
diff --git a/net/bridge/br_stp_if.c b/net/bridge/br_stp_if.c
index a285897a2fb4..1c1806d7c489 100644
--- a/net/bridge/br_stp_if.c
+++ b/net/bridge/br_stp_if.c
@@ -123,6 +123,62 @@ void br_stp_disable_port(struct net_bridge_port *p)
                 br_become_root_bridge(br);
 }
 
+static void br_stp_start(struct net_bridge *br)
+{
+        int r;
+        char *argv[] = { BR_STP_PROG, br->dev->name, "start", NULL };
+        char *envp[] = { NULL };
+
+        r = call_usermodehelper(BR_STP_PROG, argv, envp, 1);
+        if (r == 0) {
+                br->stp_enabled = BR_USER_STP;
+                printk(KERN_INFO "%s: userspace STP started\n", br->dev->name);
+        } else {
+                br->stp_enabled = BR_KERNEL_STP;
+                printk(KERN_INFO "%s: starting userspace STP failed, "
+                                "staring kernel STP\n", br->dev->name);
+
+                /* To start timers on any ports left in blocking */
+                spin_lock_bh(&br->lock);
+                br_port_state_selection(br);
+                spin_unlock_bh(&br->lock);
+        }
+}
+
+static void br_stp_stop(struct net_bridge *br)
+{
+        int r;
+        char *argv[] = { BR_STP_PROG, br->dev->name, "stop", NULL };
+        char *envp[] = { NULL };
+
+        if (br->stp_enabled == BR_USER_STP) {
+                r = call_usermodehelper(BR_STP_PROG, argv, envp, 1);
+                printk(KERN_INFO "%s: userspace STP stopped, return code %d\n",
+                        br->dev->name, r);
+
+
+                /* To start timers on any ports left in blocking */
+                spin_lock_bh(&br->lock);
+                br_port_state_selection(br);
+                spin_unlock_bh(&br->lock);
+        }
+
+        br->stp_enabled = BR_NO_STP;
+}
+
+void br_stp_set_enabled(struct net_bridge *br, unsigned long val)
+{
+        ASSERT_RTNL();
+
+        if (val) {
+                if (br->stp_enabled == BR_NO_STP)
+                        br_stp_start(br);
+        } else {
+                if (br->stp_enabled != BR_NO_STP)
+                        br_stp_stop(br);
+        }
+}
+
 /* called under bridge lock */
 void br_stp_change_bridge_id(struct net_bridge *br, const unsigned char *addr)
 {
diff --git a/net/bridge/br_sysfs_br.c b/net/bridge/br_sysfs_br.c
index 6cc5cfe665cd..7ec0b76cdd27 100644
--- a/net/bridge/br_sysfs_br.c
+++ b/net/bridge/br_sysfs_br.c
@@ -149,7 +149,9 @@ static ssize_t show_stp_state(struct device *d,
 
 static void set_stp_state(struct net_bridge *br, unsigned long val)
 {
-        br->stp_enabled = val;
+        spin_unlock_bh(&br->lock);
+        br_stp_set_enabled(br, val);
+        spin_lock_bh(&br->lock);
 }
 
 static ssize_t store_stp_state(struct device *d,